Lightning vs. USB-C
Beats Fit Pro still charge the old-fashioned way, with a wire, and to make matters more complicated for iPhone users, they use a USB-C connection to do so.
By contrast, AirPods Pro use a Lightning cable, which you’re much more likely to have handy since that’s what your iPhone uses to charge as well. The said, all of Apple’s MacBooks and most of its newest iPads also use USB-C, so it’s not like many Apple fans will have a hard time finding one of those.